Hand prosthesis

ABSTRACT

A prosthetic hand system may include a plurality of prosthetic fingers and a prosthetic thumb. The prosthetic hand system may include a thumb drive mechanism that may be used to actuate the prosthetic thumb. In some examples, the thumb drive mechanism may be configured to enable the prosthetic thumb to perform a pinching or grasping motion and a release motion. The prosthetic hand system may also include a backlock that enables the prosthetic thumb to maintain pinching or gripping pressure after a motor has been disengaged. The prosthetic hand system may also include a gear lock that may be configured to lock a finger joint. The prosthetic hand system may also include an adaptive gripping joint that may be located on each prosthetic finger. In some examples, the adaptive gripping joint may be configured to passively adapt the plurality of prosthetic fingers to one or more differently shaped objects.

PRIORITY DATA

This application is a divisional of U.S. patent application Ser. No.14/057,916, filed Oct. 18, 2013, now U.S. Pat. No. 9,320,621, whichclaims the benefit of U.S. Provisional Patent Application Ser. No.61/715,763, filed on Oct. 18, 2012, both of which are incorporatedherein by reference.

BACKGROUND

Prostheses (or prosthetics) are artificial devices that replace bodyparts (e.g., fingers, hands, arms, legs). Generally, prostheses may beused to replace body parts lost by injury or missing from birth. Thequality of prostheses has greatly improved in recent years. For example,a prosthetic limb may be molded to have the same shape and density asthe person's remaining limb. In addition, silicone skins used to formthe prosthetic limb may give the prosthetic limb a life-like appearance.As another example, improvements in prosthetic limbs may allow forincreased sensation and movement. However, prosthetic limbs stillpresent numerous challenges, particularly in the area of handling andgrasping objects. For example, hand prosthetics may have difficulty inreplicating human movements due to the number of different graspscapable by the human hand. In general, these grasps may include thelateral pinch, grasping with the thumb opposed to the fingers, thecylindrical grasp, the power grasp, and/or the handle grasp (also knownas the hook and pull).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C show an exemplary hand prosthesis system having a lateralpinch grasping position and a thumb opposition grasping position.

FIGS. 2A-2C show an exemplary thumb drive mechanism included in the handprosthesis system.

FIG. 3 illustrates an exploded view of an exemplary backlock included inthe hand prosthesis system.

FIGS. 4A and 4B illustrate a top view of an exemplary backlock includedin the hand prosthesis system.

FIG. 5 illustrates a top view of an exemplary backlock included in thehand prosthesis system.

FIGS. 6A and 6B illustrate a bottom view of an exemplary backlockincluded in the hand prosthesis system.

FIG. 7 illustrates a bottom view of an exemplary backlock included inthe hand prosthesis system.

FIG. 8 illustrates an exemplary gear lock mechanism included in the handprosthesis system.

FIG. 9 illustrates an exemplary adaptive gripping joint included in thehand prosthesis system.

DETAILED DESCRIPTION

Reference will now be made to the examples illustrated in the drawings,and specific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of thetechnology is thereby intended. Alterations and further modifications ofthe features illustrated herein, and additional applications of theexamples as illustrated herein, which would occur to one skilled in therelevant art and having possession of this disclosure are to beconsidered within the scope of the description.

FIGS. 1A-1C illustrate an exemplary hand prosthesis system. The handprosthetic system 110, 120, and 130 may include an externally-poweredhand and wrist prosthetic limb. As used herein, the terms “prosthesis,”“prosthetic,” and/or “prosthetic limb” are used interchangeably togenerally refer to any type or form of artificial limb. FIG. 1Aillustrates a hand prosthetic system 110 having a thumb member 116 inopposition to a number of finger members 112 mounted to a hand chassis118. In addition, the hand prosthetic system 110 may have a thumb axis114 of rotation.

FIG. 1B illustrates the hand prosthetic system 120 having a thumb member126 lateral to a number of finger members 128. In one exampleconfiguration, the thumb member 126 rotates on a thumb axis 122 to allowthe thumb member 126 to rotate from a position where the thumb member126 is opposite to the finger members 128 (as illustrated in FIG. 1A) toa position where the thumb member 126 is lateral to the finger members128. In particular, the thumb member 126 may rotate around the thumbaxis 114, wherein the thumb axis 114 may intersect the finger-tip areawhen the finger members 128 are flexed in a common grasping orientation.In one example, the thumb rotation assembly 124 can be configured toenable the thumb member 126 to be moved passively from either a fingeropposing position to a finger lateral position or a finger lateralposition to a finger opposing position. In another example, a motor canbe mounted to a hand chassis 118 and the motor can be connected to athumb rotation assembly 124 enabling the thumb rotation assembly 124 torotate on the thumb axis 122 from either a finger opposing position to afinger lateral position or a finger lateral position to a fingeropposing position.

FIG. 1C illustrates the hand prosthesis system 130 with a thumb axis132, which may allow the thumb member 138 to rotate from a thumbopposition grasping position to a lateral pinch grasping position. Asshown in FIG. 1C, and as discussed in greater detail below, the handprosthetic system 130 may include a thumb drive mechanism. In someexamples, the thumb drive mechanism may utilize a rod-end bearing 134and an output gear 136 to enable the thumb member 138 to actuate. In oneexample, operating the thumb drive mechanism can cause the thumb member138 to perform a pinching action. Depending upon the position of thethumb member 138 along the thumb axis 132, operating the thumb drivemechanism can produce a pinch gripping action that is lateral to thefinger members 140 or a pinch gripping action that is opposing to thefinger members 140. In some examples, rotation of the thumb member 138from the lateral pinch position to the finger opposition position mayallow for enhanced grasp for a person using the hand prosthesis system130.

FIGS. 2A-2C show an exemplary thumb drive mechanism included in a handprosthesis system 210, 220 and 230. The hand prosthesis system 210 inFIG. 2A may include a thumb drive mechanism 211 comprising a drive crank212, a rod-end bearing 214, a gear 216, and/or a driven crank 218. Inone example, the gear 216 in the thumb drive mechanism 211 may be incommunication with the drive crank 212, which in turn may be coupledwith a spherical bearing on a first end of the rod-end bearing 214,where the rod-end bearing 214 may drive a link to another sphericalbearing on a second end of the rod-end bearing 214. As a result, drivingthe drive crank 212 in a first direction (e.g., clockwise) may cause thethumb member 213 to actuate and perform a pinch motion. Driving thedrive crank 212 in a second direction (e.g., counter clockwise) maycause the thumb member 213 to actuate and perform a release motion. Inaddition, the thumb drive mechanism can include a motor (i.e., anelectric motor) mounted within a hand chassis of the hand prosthesissystem 210, 220 and 230, the motor being operable to drive the drivecrank 212 via the gear 216. In one example, the motor may be incommunication with a first stage gear that is engaged with a secondstage gear attached to the drive crank 212. Thus, when power is suppliedto the motor, the motor drives the first stage gear which in turn drivesthe second stage gear.

The described configuration of the hand prosthesis system 210 in FIG. 2Amay allow the thumb member 213 to be passively positioned laterally tothe finger members 215. Alternatively, the thumb member 213 may bepassively positioned opposing the finger members 215. As illustrated inFIG. 2B, the hand prosthesis system 220 may include a thumb axis ofrotation 222 angled forward from a hand chassis axis 226 to a predefinedangle 224. In one example configuration, the predefined angle 224 may beconfigured to an angle within a range of about 20 degrees to 30 degrees.In a specific example, the predefined angle 224 may be configured toabout 26 degrees. By angling the thumb axis of rotation 222 forward fromthe hand chassis axis 226 by the predefined angle 224, the thumb member228 rotates from a lateral position to an opposing position withrelatively little translation. In addition, angling the thumb axis ofrotation 222 by the predefined angle 224 may allow the thumb member 228,when actuated, to be positioned near the fingertips of the fingermembers for optimal grasp.

FIG. 2C illustrates an additional view of the hand prosthesis system230, including a gear 232, a drive crank 234, a rod-end bearing 236, aload cell 238, and/or a driven crank 240. In one example configuration,the load cell 238 may be situated between a first casing and a secondcasing of the rod-end bearing 236. The load cell 238 may be configuredto detect a load amount being applied by the system. For example, theload cell 238 may be a strain gauge load cell configured to detect whena force applied by the drive crank 234 via a motor may be at, ornearing, a force (i.e., load amount) that exceeds a predeterminedthreshold.

FIG. 3 illustrates an exploded view of an exemplary backlock 300included in the hand prosthesis system. In some example configurations,the backlock 300 may be included in a thumb drive mechanism of anexternally-powered hand prosthesis system. The backlock 300 may allowinput torque (e.g., torque produced by a motor) in either direction(i.e., forward or reverse) to be transferred through the thumb drivemechanism to a thumb member causing the thumb member to actuate. Forexample, the backlock 300 may allow torque to be applied to an input(e.g., a drive cog 306) of the backlock 300 thereby unwinding a spring308 from around a core element 312. Once the spring 308 is unwound fromaround the core element 312, the thumb drive mechanism may be free fromthe restraint of the spring 308 and can therefore drive an associatedthumb member (i.e., cause the thumb member to perform a pinch/graspmotion or release motion). Further, the backlock 300 may allow outputtorque (e.g., back pressure produced by input torque) to cause thespring 308 to wrap around the core element 312 thereby restraining thethumb drive mechanism and preventing the movement of the thumb member.As a result, grasped objects by the hand prosthesis system may remainsecure when electrical power is terminated to a motor of the thumb drivemechanism, thereby saving battery life.

As illustrated in FIG. 3, the backlock 300 may include an output element302, an outer spring driver 304, a drive cog 306, a spring 308, an innerspring driver 310, and/or a core element 312. In some exampleconfigurations, the output element 302 may be towards the top of thebacklock 300, and the core element 312 may be towards the bottom of thebacklock 300. Additionally, the output element 302 may cause outputtorque to act on the wrap sides of the inner spring driver 310 and theouter spring driver 304. In one example, the inner spring driver 310 mayact on the spring 308 in the direction towards the bottom of thebacklock 300, while the outer spring driver 304 acts on the spring 308in the direction towards the top of the backlock 300. In anotherexample, the spring 308 may provide the necessary force to wrap aroundthe core element 312, or in the contrary, the spring 308 may provide alack of force to unwrap around the core element 312.

FIGS. 4A and 4B illustrate a top view of the backlock 410 and 430included in a hand prosthesis system. FIGS. 4A and 4B illustrate thebacklock 410 and 430 in an unwrapped position, where an output elementmay be hidden. FIG. 4A includes a core element 412, a spring 414, aninner spring driver 416, an outer spring driver 418, and/or a drive cog420. FIG. 4B further illustrates that the outer spring driver 432 may betransparent.

In one example configuration, an input of the backlock 410 and 430 maybe a link element, shaft element or some other input element that is incommunication with the drive cog 420. In an example of the backlock 410and 430, an input may be configured such that when torque is applied tothe input of the backlock 410 and 430, the torque causes the drive cog420 to unwrap the spring 414 from around the core element 412. Morespecifically, torque applied to the input of the backlock 410 and 430cause the drive cog 420 to rotate and engage the outer spring driver418. The drive cog 420 and the outer spring driver 418 then rotatetogether and engage the inner spring driver 416, thereby unwrapping thespring 414 from around the core element 412.

In another example, the output element of the backlock 410 and 430 maybe configured to enable the spring 414 to wrap around the core element412 when torque is applied to the output element. More specifically, theoutput element can engage the drive cog 420 thereby rotating the drivecog 420 until the inner spring driver 416 is engaged by the drive cog420. The output element and the inner spring driver 416 then rotatetogether until the outer spring driver 418 is engaged by the outputelement and the inner spring driver 416, thereby allowing the spring 414to wrap around the core element 412.

FIG. 5 illustrates a top view of the backlock 300 shown in FIG. 3 thatcan be included in a hand prosthesis system. In some embodiments, torquemay apply to the drive cog 420 in the clockwise direction, asillustrated in 510. As a result, the drive cog 420 may rotate untilhitting the outer spring driver 418, as illustrated in 520. Subsequentto the drive cog 420 hitting the outer spring driver 418, both the drivecog 420 and the outer spring driver 418 may rotate together untilhitting the inner spring driver 416. At this point, the spring 414 maybe unwrapped by the length 532 that the outer spring driver 418 travelsbefore hitting the inner spring driver 416, as illustrated in 530. Theunwrapping of the spring 414 can be enough to clear the core element 412of the spring 414, thereby allowing the torque from the input (i.e., viathe drive cog 306) of the backlock 300 to transfer to the output (i.e.,via the output element 302) of the backlock 300. In some examples, thetorque may transfer from the input to the output with a relatively smallamount of drag. When the outer spring driver 418 proceeds to hit theinner spring driver 416, both the outer spring driver 418 and the innerspring driver 416 may rotate with the input torque, as illustrated in540.

FIGS. 6A and 6B illustrate a bottom view of the backlock 300 included inthe hand prosthesis system. FIGS. 6A and 6B illustrate the backlock 610and 630 in a wrapped position. FIG. 6A includes an output element 612,an inner spring driver 614, a drive cog 616, an outer spring driver 618,and/or a core element 620. FIG. 6B may include a spring 632. Inaddition, FIG. 6B also illustrates that the core element 620 may betransparent 634. In some example configurations, applying torque to theoutput may result in the output element 612 being moved, thereby actingon the inner spring driver 614. In other example configurations,applying torque to the output may result in the output element 612 beingmoved, thereby acting on the outer spring driver 618. In some exampleconfigurations, the output element 612 may act on the inner springdriver 614 counter-clockwise when viewed looking down on the coreelement 620. In other examples, the output element 612 may act on theouter spring driver 618 clockwise when viewed looking down on the coreelement 620.

FIG. 7 illustrates a bottom view of the backlock 300 included in a handprosthesis system. In some examples, torque may be applied to the outputelement 612 in the counter-clockwise direction, as illustrated in 710.As a result, the drive cog 616 may rotate until hitting the inner springdriver 614, as illustrated in 720. Subsequent to the drive cog 616hitting the inner spring driver 614, both the drive cog 616 and theinner spring driver 614 may rotate together until hitting the outerspring driver 618. At this point, the spring 632 may be wrapped by thelength 732 that the inner spring driver 614 travels before hitting theouter spring driver 618, as illustrated in 730.

Continuing with FIG. 7, the wrapping of the spring 632 may be enough forthe spring 632 to firmly hold the core element 620. In other words, thewrapping of the spring 632 may be enough for the spring 632 to grip thecore element 620. In some examples, the firm hold on the core element620 may provide a calculated torque. In one example, the spring 632 maybe a torsion spring providing a torque rating within a range of about 20inch ounces of torque to about 30 inch ounces of torque. In a specificexample, the calculated torque may be about 25 in-ozs. In otherexamples, the calculated torque may be a different numerical value. Ingeneral, the spring 632 may begin to lose its hold (e.g., slip) on thecore element 620 if a torque greater than the calculated value isapplied to the output element 612, thus, providing an overloadprotection for a prosthetic hand drive mechanism. Thus, a high loadapplied to a thumb member may result in the backlock slipping, ratherthan breaking. In some examples, a torque greater than 25 in-oz. appliedto the output 612 may cause the spring 632 to lose its hold on the coreelement 620. As a result of the spring 632 slipping on the core element620, the backlock rotates, as illustrated in 740.

FIG. 8 illustrates an exemplary gear lock mechanism 800 that may beincluded in the hand prosthesis system. In an example configuration, thegear lock mechanism 800 may be implemented in a finger joint. In aspecific example, the gear lock mechanism 800 may be included in anexternally-powered hand and wrist prosthetic system. The gear lockmechanism 800 includes a distal finger link 802, a proximal finger link804, a first internal gear 806, a spring 808, a second internal gear810, and/or a button and an external gear 812 with an attached button.In an example, the first internal gear 806 may be attached to the distalfinger link 802, while the second internal gear 810 may be attached tothe proximal finger link 804. In some examples, the first internal gear806 and the second internal gear 810 may be mounted by means of acompliant member, thereby providing natural compliance and/orspringiness to the joint. This springiness may also allow for benefitsthat result from having a “series-elastic-element” in the drive whendoing force control. In some examples, the gear lock mechanism 800 mayinclude an external gear that is coupled to a lock button 812. Forexample, the external gear coupled to the lock button 812 may be used tobridge between the first internal gear 806 and the second internal gear810, thereby locking the finger joint. In some examples, the gear lockmechanism 800 may include a spring 808. For example, the spring 808 maybe used to return the button 812 with the external gear to a lockedposition. Alternatively, the spring 808 may be used to return the button812 to an unlocked position. In other embodiments, the spring 808 mayreturn the first and second internal gears 806 and 810 to a lockedposition. In some examples, the first internal gear 806 attached to thedistal finger link 802 may be coupled to the link via a servo clamp. Inother examples, the second internal gear 810 attached to the proximalfinger link 804 may be coupled to the link via a servo clamp. The servoclamp may slip when overloaded, thereby providing an overload protectionfor the gear locking mechanism.

FIG. 9 illustrates an adaptive gripping joint 900 that may be includedin a hand prosthesis system. The adaptive gripping joint 900 may includea one-way bearing 902, an unlock button 904, a servo clamp 906, a balllocking mechanism 908, and/or a spring 910. In some embodiments, theunlock button 904 may include a spring return, while the spring 910 mayextend the distal link when unlocked. In some embodiments, the adaptivegripping joint 900 may allow the fingers to passively adapt to a varietyof different shaped objects. For example, the adaptive gripping joint900 may allow a prosthetic joint to flex into a desired position. Insome examples, the one-way bearing 902 may allow the finger to flexagainst a grasped object. In other examples, the one-way bearing 902 mayallow the finger to flex into a grasped object. In one exampleconfiguration, the one-way bearing 902 allows the finger to not extenduntil the ball locking mechanism 908 is disengaged. For example, theball locking mechanism 908 may be disengaged by pressing the unlockbutton 904, wherein the unlock button 904 may be located on the side ofthe hand.

The described features, structures, or characteristics may be combinedin any suitable manner in one or more examples. In the precedingdescription, numerous specific details were provided, such as examplesof various configurations to provide a thorough understanding ofexamples of the described technology. One skilled in the relevant artwill recognize, however, that the technology can be practiced withoutone or more of the specific details, or with other methods, components,devices, etc. In other instances, well-known structures or operationsare not shown or described in detail to avoid obscuring aspects of thetechnology.

Although the subject matter has been described in language specific tostructural features and/or operations, it is to be understood that thesubject matter defined in the appended claims is not necessarily limitedto the specific features and operations described above. Rather, thespecific features and acts described above are disclosed as exampleforms of implementing the claims. Numerous modifications and alternativearrangements can be devised without departing from the spirit and scopeof the described technology.

What is claimed is:
 1. A gear locking mechanism for a prosthetic hand,comprising: a first internal gear attached to a distal finger link of afinger member; a second internal gear attached to a proximal finger linkof the finger member; an external gear coupled to a button, wherein theexternal gear forms a bridge between the first internal gear and thesecond internal gear to lock a finger joint of the finger member; and aspring configured to return the button to a locked position, wherein thefirst internal gear or second internal gear is coupled to a servo clampattached to a respective distal finger link or proximal finger link,thereby providing an overload protection for the gear locking mechanism.2. A gear locking mechanism for a prosthetic hand as in claim 1, furthercomprising a compliant member that is attached to a finger link and aninternal gear, wherein the compliant member acts as aseries-elastic-element providing flexibility within the finger link.